Add Checkout Stripe redirect logic to get users redirected to stripe authentication pages provided by the stripe API

app/controllers/checkout_controller.rb

@@ -170,6 +170,7 @@ class CheckoutController < Spree::StoreController
 
   def redirect_to_payment_gateway
     redirect_path = Checkout::PaypalRedirect.new(params).path
+    redirect_path = Checkout::StripeRedirect.new(params, @order).path if redirect_path.blank?
     return if redirect_path.blank?
 
     render json: { path: redirect_path }, status: :ok

app/services/checkout/stripe_redirect.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+# Provides the redirect path if a redirect to the payment gateway is needed
+module Checkout
+  class StripeRedirect
+    def initialize(params, order)
+      @params = params
+      @order = order
+    end
+
+    # Returns the path to the authentication form if a redirect is needed
+    def path
+      return unless stripe_payment_method?
+
+      payment = @order.pending_payments.last
+      return unless payment&.checkout?
+
+      payment.authorize!
+      raise unless payment.pending?
+
+      payment.cvv_response_message if url?(payment.cvv_response_message)
+    end
+
+    private
+
+    def stripe_payment_method?
+      return unless @params[:order][:payments_attributes]
+
+      payment_method_id = @params[:order][:payments_attributes].first[:payment_method_id]
+      payment_method = Spree::PaymentMethod.find(payment_method_id)
+      payment_method.is_a?(Spree::Gateway::StripeSCA)
+    end
+
+    def url?(string)
+      return false if string.blank?
+
+      string.starts_with?("http")
+    end
+  end
+end

spec/controllers/checkout_controller_spec.rb

@@ -251,7 +251,7 @@ describe CheckoutController, type: :controller do
     end
 
     it "should check the payment method for Paypalness if we've selected one" do
-      expect(Spree::PaymentMethod).to receive(:find).with(payment_method.id.to_s) { payment_method }
+      expect(Spree::PaymentMethod).to receive(:find).twice.with(payment_method.id.to_s) { payment_method }
       allow(order).to receive(:update_attributes) { true }
       allow(order).to receive(:state) { "payment" }
       spree_post :update, order: { payments_attributes: [{ payment_method_id: payment_method.id }] }

spec/services/checkout/paypal_redirect_spec.rb

@@ -3,7 +3,7 @@
 require 'spec_helper'
 
 describe Checkout::PaypalRedirect do
-  describe '#order_params' do
+  describe '#path' do
     let(:params) { { order: { order_id: "123" } } }
 
     let(:redirect) { Checkout::PaypalRedirect.new(params) }

spec/services/checkout/stripe_redirect_spec.rb

@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Checkout::StripeRedirect do
+  describe '#path' do
+    let(:order) { create(:order) }
+    let(:params) { { order: { order_id: order.id } } }
+
+    let(:redirect) { Checkout::StripeRedirect.new(params, order) }
+
+    it "returns nil if payment_attributes are not provided" do
+      expect(redirect.path).to be nil
+    end
+
+    describe "when payment_attributes are provided" do
+      it "raises an error if payment method does not exist" do
+        params[:order][:payments_attributes] = [{ payment_method_id: "123" }]
+
+        expect { redirect.path }.to raise_error ActiveRecord::RecordNotFound
+      end
+
+      describe "when payment method provided exists" do
+        before { params[:order][:payments_attributes] = [{ payment_method_id: payment_method.id }] }
+
+        describe "and the payment method is not a stripe payment method" do
+          let(:payment_method) { create(:payment_method) }
+
+          it "returns nil" do
+            expect(redirect.path).to be nil
+          end
+        end
+
+        describe "and the payment method is a stripe method" do
+          let(:distributor) { create(:distributor_enterprise) }
+          let(:payment_method) { create(:stripe_sca_payment_method) }
+
+          it "returns the redirect path" do
+            stripe_payment = create(:payment, payment_method_id: payment_method.id)
+            order.payments << stripe_payment
+            allow(stripe_payment).to receive(:authorize!) do
+              # Authorization moves the payment state from checkout/processing to pending
+              stripe_payment.state = 'pending'
+              true
+            end
+            test_redirect_url = "http://stripe_auth_url/"
+            allow(stripe_payment).to receive(:cvv_response_message).and_return(test_redirect_url)
+
+            expect(redirect.path).to eq test_redirect_url
+          end
+        end
+      end
+    end
+  end
+end